Test Stands: Part Two

Published On July 11, 2017

Regen Drive

Challenge

The Clemson University International Center for Automotive Research (CU-ICAR) researchers where pondering how to use an electric motor to load an engine and increase their ability/flexibility in different testing scenarios. They contacted ABB and ABB called us to sit down with their key engineering researchers to outline needs and create an action plan.

Mark MacIlwain, our B&D Technologies Account Manager (Simpsonville, SC) and a Clemson engineering graduate, and I met with Dr. Mark Hoffman and listened as he outlined his vision of what the test stand needed to do and the performance requirements. We translated his requests into a proposal and design project for the University.

Background

In 2003, CU-ICAR was simply an idea. A decade later, the vision is a reality. What was once a dream, is today a vibrant campus.

CU-ICAR Vision: To be the premier automotive research, innovation and educational enterprise in the world.

CU-ICAR Mission: Be a high seminary of learning, in the field of automotive engineering; lead translational research, with emphasis on industry relevance, and support with excellence in basic research; contribute to high value job creation in South Carolina; lead global thinking on the sustainable development of the automotive sector

Despite the early stage of our development, we have been diligently measuring and monitoring our growth and success to date. It is important to see our progress in quantifiable terms, and below we lay out these figures.

CU-ICAR EDUCATION:

95% of students are gainfully employed in the automotive industry

Global student population representing 17 countries

26% of our alumni are employed in the state of SC

183 total M.S. and PhD degrees awarded

4 Endowed Chairs in 4 key research areas:

Timken Endowed Chair in automotive design and development

BMW Endowed Chair in automotive systems integration

BMW Endowed Chair in automotive manufacturing

Michelin Endowed Chair in vehicle electronic systems integration

The Plan

Since B&D Technologies has deployed several test stands for automotive and aerospace, the design was pretty straight forward. ABB/Baldor had already gathered the data on the dual motor design using a custom RPMAC Motor. We had to finish the motor, add an encoder to fit on the unique dual shaft motor, and of course come up the drive and control design.

100HP ACS800 regen drive in a custom drive enclosure with all of the equipment to create a standalone drive system

The drive design allowed the researchers to use velocity control and torque control. In velocity mode, the accel/decel times where fully adjustable. The design also had hooks via Fieldbus and analog signals to port over to any future data storage and analysis system the university wants to deploy at a later date.

A sample of the performance with the design in velocity mode:

Reception and Testing

To date the system has been used quite frequently to test various engine designs and modifications for things like combustion efficiency, combustion chamber sizing, low temperature combustion design, fuel injector design and many others. Please take a look at the application pictures.

A sample of the performance in velocity mode with a very hard stop:

Opinion

Test stands are no more difficult than regular applications. The challenges arise with the type of dynamics involved and the ability for the drive/motor/gearing to produce the simulated environment. The last piece is always to get the key performance data out of the drive. The data is always created but not always needed based on the researcher’s methods of getting feedback. If the researcher has external means to collect specific data like fuel consumption, then the correlation between load speed may not be a valid data point whether it is available or not. It just depends on the scope of the experiment.

Like velocity mode, torque mode is always wanted in a simulation environment, IMHO, it is not always needed. In most cases, I set the drive up with the ability to switch back and forth between torque and velocity mode, but it is seldom or never switched to torque.

Other questions of resolution like 8-bit, 12-bit, 16-bit come up and does the drive back calculate things like AC Bus voltage from the real measurement of the DC bus. If so, then the researcher may be better off adding a line voltage measurement probe to get a more accurate measurement.

Last Words

Like I talk about in a great deal of posts, the great differentiator behind drive applications is knowledge. With the baby-boomers retiring at a rate of 10,000 workers per day, it is imperative that universities, like Clemson, produce the next generation of engineers, but also produce graduates who are genuinely passionate about new discovery and testing convention.